MVC is an architectural pattern (a reusable solution to a common problem) that tackles a hodge-podge styled codebase by dividing the application into three distinct, interconnected components:

1. Model (M): The Data and Business Logic
2. View (V): The User Interface
3. Controller (C): The Orchestrator/Handler

1. Model (M): The Data & Brains

• What it is: Represents the application’s data and the rules that govern it (business logic). It’s the “truth” of your application state.
• What it does:
  • Manages data (fetching from database, saving to database, interacting with APIs).
  • Enforces data consistency and validation rules (e.g., “email must be valid,” “price cannot be negative”).
  • Performs calculations or operations directly related to the data.
  • Crucially: It knows nothing about how the data will be displayed (no HTML, no GUI widgets here). It just holds and manages the raw information and logic.s
• Python Context:
  • Classes representing your core concepts (e.g., User, Product, Order).
  • Database interaction code (using ORMs like SQLAlchemy or Django ORM, or direct DB-API calls).
  • Functions or methods for validation and calculations.
  • Often plain Python classes and functions.

2. View (V): What the User Sees

• What it is: Responsible for presenting the data (from the Model) to the user and sending user commands/input to the Controller. It’s the User Interface (UI).
• What it does:
  • Displays data it receives (usually passed from the Controller).
  • Formats the data for presentation (HTML, GUI layout, JSON structure).
  • Captures user interactions (button clicks, form submissions, key presses).
  • Crucially: It generally doesn’t contain much logic. It’s often considered “dumb” – its main job is presentation and capturing input. It doesn’t modify data directly.
• Python Context:
  • HTML Templates (Jinja2, Django Templates).
  • GUI Widgets (Tkinter buttons/labels, PyQt elements).
  • Functions that generate JSON/XML responses for APIs.
  • Functions that print formatted output to the console.

3. Controller (C): The Handler/Orchestrator

• What it is: Acts as the intermediary between the Model and the View. It handles user input and updates the Model or View as necessary.
• What it does:
  • Receives user input/requests (from the View or the framework’s routing).
  • Interprets the input (e.g., “user wants to see profile,” “user submitted new data”).
  • Interacts with the Model (e.g., model.get_user(id), model.save_new_user(data)).
  • Selects the appropriate View to display.
  • Passes data from the Model to the View for rendering.
• Python Context:
  • Flask route handler functions (@app.route(‘/users’) def show_users(): …).
  • Django “views” (confusingly named, they act as Controllers in MVC).
  • Event handler functions in GUI applications (e.g., on_button_click()).
  • Functions that process command-line arguments.

• Flask: Less opinionated, doesn’t enforce MVC strictly, but naturally encourages it.
  • Model: You typically bring your own (like SQLAlchemy) or write custom data-handling code.
  • View: Usually Jinja2 templates.
  • Controller: Route handler functions (@app.route(…)).

Blueprints as the Solution: Modularization: